Current control apparatus



Dec. 18, 1934. w LYLE CURRENT CONTROL APPARATUS Filed Oct. 6, 1930 2 Sheets-Sheet 1 INVENTOR fiedar/z'k W L;

ATTORNEY Dec. 18, 1934. F. w. LYLE CURRENT CONTROL APPARATUS Filed 001;. 6'; 1930 2 Sheets-Sheet 2 All:

I INVENTOR Frederick Ml. Lyle ATJIORNEY Patented Dec. 18, 1934 UNITED STATES PATENT OFFICE 1,985,044 CURRENT CONTROL APPARATUS Application October 6, 1930, Serial No. 486,689

My invention relates to a, current-control apparatus and more particularly to apparatus in which the intensity of illumination supplied icy lighting circuits is varied in a predetermined manner, such as is used in theatres and auditoriums or for general interior or exterior orna mental lighting.

An object of my invention is to provide automatic means by which the intensity oi the ii lumination may be controlled in a predetermined manner during the scenes of a theatrical production or over any selected time intervals.

Another object of my invention is to provide a system of lighting control which will be ex tremely flexible, allowing any desired sequence of changes in the intensity or" the illumination.

Another object of my invention is to provide a system in which current in an electric circuit may be subjected to control in accordance with a desired program, and in which a very simple, cheap and readily alterable device may he employed to pro-define that program.

A further object of my invention is to provide a system of lighting control of the preset, multi-scene theatre switchboard type in which the degree of illumination at any period during the sequence of changes may he changed as he desired. V

These and other objects will he made apparent throughout the further description of the vention.

As one embodiment 0:? my invention, an hating-current lighting circuit is controlled through a reactor having a direct-current control winding. The control winding supplied with current from a light-sensitive device through an amplifier. The amount of light iall= ing on the light-sensitive device is varied toy means of a strip of translucent paper or the like on which appropriately varied areas have been blocked-in and which is passed between a source of light and the light-sensitive device to vary the amount of light striking the light-sensitive A device. in this way, the intensity of illumination is varied according to any desired program corresponding to the varying amount of light falling on the light-sensitive device. The apparatus by which this invention may be practiced is shown in the drawings, in which Figure 1 is a schematic diagram illustrating the apparatus and the circuits connected there= with for controlling a single lighting circuit.

Fig. 2 is a side view of a portion of the control strip and the aperture plate.

Pig. 3 is a similar view of a modified control strip.

Fig. 4 is a diagram or a modified circuit which may he used in the same manner as the circuit shown in Fig. l.

Fig. 5 is a schematic diagram sho the apparatus and the circuits ior controlling two independent lighting circuits.

Referring particularly to Fig. l, a single light lug circuit 3'. is illustrated having lamps 2 sup plied iro a source of alternating current 3 through inductive windings d on a reactor 5. llhe reactor 5 comprises an iron core having legs 6, l and o, with the inductive alternatingcurrent windings d on legs ii and 8. The normal inductance of the windings l is such that the lamps 2 will not he lighted. A direct-current control winding ii is provided on the central leg 7 of the reactor.

lhe winding 9 serves to saturate the core and thereby reduce the impedance oi the coils l suicstantially in accordance with the current flowing through the control The winding E9 is energized by a battery it through a three-electrcde vacuum tube ll wmch has a plate 12, a grid 13 and a filament The filament is lighted by a battery 15 through a variable resistance id. The potential impressed on the grid is controlled by the potential drop across the resistance ii, the cur rent through which is controlled by a light sen sitive device, such as photo-electric cell it! having a cathode 3i and an anode 32. Potential is applied across the photo-electric cell by a hat= tery it.

The amount oi light from a source 20 strikes the light-sensitive device it is controlled icy a strip or him 21 which is moved between the 2c and t e light-sensitive device it. The strip 21 is made of some translucent material, such as paper, cloth or celluloid.

The amount or light which is allowed to pass through the strip 2i to strike the photo-electric cell is controlled icy making a portion of its width opaque, as indicated at 33. For example, as shown in Fig. 2, ii the full intensity of illurnl= nation is desired up to a given time, corresponding to the line 22 on the strip, it will he translucent across its full width up to that point, as at so. If it is then desired to have the intensity of illumination gradually decrease to one half of its initial value, during a period or time represented by the distance between the dotted lines 22 and 23, the strip will he made opaque by blackening a part of its width irom one edge to the line 35. Thus, the translucent part of the strip has been narrowed from full width at line 22 until only a part of the strip is translucent at the line 23. If it is then desired to continue with this degree of illumination, the width of the opaque portion will be made constant, as at 36.

The means used for blackening or rendering a portion of the strip opaque may be pencil, ink, or paint, but, in any case, it is desirable that it be of such character that it may be readily erased or washed ofi. This will permit changes in the degree of illumination given by the light-=- ing circuit to be readily made, they may be come desirable, by merely altering the width of p que portion of the strip. The width of translucent area required to produce any required intensity or" the theatre lights may readily be determined by trial in advance, thus giving data for plotting any desired. light program on the control-strip.

An aperture plate 24, having a slit 25, is placed between the light source 20 and the strip 21. As the strip is moved past the light-sensitive device it and the aperture plate, the amount of light striking the light sensitive device is controlled by the width of the portion of the strip which has been left translucent.

In Fig. 3, another modification o! the strip 21 is shown. In this modification, the amount of light which is allowed to pass is varied by having the translucence of the strip varied over its whole width, according to the amount of light which it is desired shall be passed. Fig. 3 is drawn to represent the same change in illumination as does Fig. 2. The strip is fully translucent at 37 and gradually decreases in translucence at St during the period from lines 22 to 23 where one half the normal amount oi light is allowed to pass. Wis is then kept constant after line 23 as at 32.

The strip 2i is fed from a roll 26, across the beam of light, to the roll 27. The roll 27 is driven by a suitable motor 28 supplied with power through lines 29. A speed-control device is indicated at 30 for vamng the speed of the motor. This is desirable in order to vary the total time over which the given series of lighting changes are to take place. This is particularly desirable when the apparatus is used for theatrelighting control, since the total time taken by any scene may be increased because of slower action by the players or because of interruptions by applause.

While the apparatus is illustrated as using a reactor for controlling the lighting circuit, it is apparent that other control means may be used. For example, a resistance, the value of which is varied by a solenoid, which is actuated by the direct-current control winding, may be used.

The amplifier has been shown as consisting of a single three-electrode vacuum tube 11. Additional stages of amplification may be used if desired, or other amplification means may readily be used.

It will be seen also that amplifiers and relays of various types may be applied to amplify the output of photo-cell 18 sufllciently to regulate the current in a load circuit. For example, the lighting current itself may traverse a grid-controlled tube 41 connected as shown in Fig. 4..

Potential of control grids 13' therein is varied.

by photo cell 18 and resistor 17 in the same way as in the apparatus of Fig. 1. When grids 13 are sufilciently negative in potential, no curaccuses rent can flow in mercury-arc tube 41 and substantially no current flows from alternating-current source 3, through transformer 42, to load circuit 1. When grids 13' are not so negatively charged by current flow in resistor 17, current passes alternately irom each anode 12' to cathode 14' of tube 41; and a corresponding alternating current flows, through transformer 42, to load circuit 1.

Tube 41 may be a grid-controlled mercuryarc tube or a gas-filled hot-cathode tube or a cold-cathode grid-glow tube.

It will be evident that other well-known ways of forming a strip oi varying transluccncy, such as ordinary photographic processes, may be de sirably employed under certain circumstances.

The drawings illustrate the use oi only two lighting circuits but it should be understood that most installations, such as in theatres, will require a large number oi circuits of various colored lights which may be controlled individually or in groups. In order that each of the various groups of circuits may be controlled in a predetermined manner, it is desirable that the control strips for all of the circuits be driven by a. single motor in order that they may be kept in synchronism.

If it is desired to control a group of circuits, a single light source may be used with its beam split to traverse the translucent strips controlling several individual circuits. The total amount of illumination on any scene may then be varied, without changing the relative amounts of light supplied by each circuit, by varying the amount of light from source 20. This may be accomplished by use of a rheostat 43, by a shutter, or by an additional translucent strip having portions allowing the passage of diflerent amounts of light, which may be passed in iront oi the light source.

From the foregoing description, it is seen that a theatre-lighting control system is provided of extreme flexibility, in that any desired sequence of changes in the degree or illumination may be obtained by merely plotting them on the control strip. This use of a photoelectric cell and control strip is particularly advantageous in that the use of potentiometers or variable resistances, with their accompanying'limitations, is entirely eliminated.

It will, however, be evident that, while the system here described is applied to the control oi theatre lights, the output current of the tube 11 may flow in any circuit in which current flow in accordance with a predefined program is desired, and that the ease with which the program can be charted with ordinary writing materials on a simple transparent ribbon, and, upon occasion, can be altered at a moments notice, tageous in control generally.

While I have illustrated and described particular embodiments of the invention, it will be recognized that they are merely by way of 11- lustrating the broad principles of my invention which are of wide application, and that changes may be effected therein without departing irom the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. In an illumination-control system, in combination, a plurality of lighting circuits, 9. reactor for controlling each of said circuits, 9. conitrol winding on each reactor, 9, source of cur- 'rent for the control windings, light-responsive means for varying the control current ineach is advanwinding, a common source of light for energizing all of said light-responsive means, means for independently varying the amount of light striking each of said light-responsive means to vary the illumination supplied by each lighting circuit independently of the other circuits, and means for varying the intensity of said common source of light to vary simultaneously the illumination supplied by all the lighting circuits.

2. In an illumination-control system, in combination, a plurality of lighting circuits, a reactor for controlling each of said circuits, a control winding on each reactor, a source of current for the control windings, light-responsive means for varying the control current in each winding, 2. common source of light for energizing all of said light-responsive means, variable translucent -means for independently varying the amount of light striking each of said lightresponsive means to vary the illumination supplied by each lighting circuit independently of the other circuits, and means for varying the intensity of said common source of light to vary simultaneously the illumination supplied by all the lighting circuits.

3. In an illumination-control system, in combination, a plurality of lighting circuits, magnetic-amplifying means for controllingeach of said circuits, light-responsive means for controlling the energization of the magnetic-amplilying means, a common source of light for energizing all of said light-responsive means, means for independently varying the amount of light striking each of said light-responsive means to vary the illumination supplied by each lighting circuit independently of the other circuits, and means for varying the intensity of said common source of light to vary simultaneously the illumination supplied by all the lighting circuits.

FREDERICK W. LYLE. 

